Contaminant removal from hydrocarbon streams with lactamium based ionic liquids

ABSTRACT

A process for removing a contaminant from a hydrocarbon stream using a lactamium based ionic liquid is described. The process includes contacting the hydrocarbon stream comprising the contaminant with a lean hydrocarbon-immiscible lactamium ionic liquid to produce a mixture comprising the hydrocarbon and a rich hydrocarbon-immiscible lactamium ionic liquid comprising at least a portion of the removed contaminant; and separating the mixture to produce a hydrocarbon effluent and a rich hydrocarbon-immiscible lactamium ionic liquid effluent comprising the rich hydrocarbon-immiscible lactamium ionic liquid.

BACKGROUND OF THE INVENTION

Various hydrocarbon streams, such as vacuum gas oil (VGO), light cycleoil (LCO), and naphtha, may be converted into higher value hydrocarbonfractions such as diesel fuel, jet fuel, naphtha, gasoline, and otherlower boiling fractions in refining processes such as hydrocracking andfluid catalytic cracking (FCC). However, hydrocarbon feed streams forthese materials often have high amounts of nitrogen which are moredifficult to convert. For example, the degree of conversion, productyields, catalyst deactivation, and/or ability to meet product qualityspecifications may be adversely affected by the nitrogen content of thefeed stream. It is known to reduce the nitrogen content of thesehydrocarbon feed streams by catalytic hydrogenation reactions such as ina hydrotreating process unit. However, hydrogenation processes requirehigh pressures and pressure

Various processes using ionic liquids to remove sulfur and nitrogencompounds from hydrocarbon fractions are also known. U.S. Pat. No.7,001,504 discloses a process for the removal of organosulfur compoundsfrom hydrocarbon materials which includes contacting an ionic liquidwith a hydrocarbon material to extract sulfur containing compounds intothe ionic liquid. U.S. Pat. No. 7,553,406 discloses a process forremoving polarizable impurities from hydrocarbons and mixtures ofhydrocarbons using ionic liquids as an extraction medium. U.S. Pat. No.7,553,406 also discloses that different ionic liquids show differentextractive properties for different polarizable compounds.

There remains a need in the art for improved processes that enable theremoval of contaminants from hydrocarbon streams.

SUMMARY OF THE INVENTION

One aspect of the invention is process for removing a contaminant from ahydrocarbon stream. In one embodiment, the process includes contactingthe hydrocarbon stream comprising the contaminant with a leanhydrocarbon-immiscible lactamium ionic liquid to produce a mixturecomprising the hydrocarbon and a rich hydrocarbon-immiscible lactamiumionic liquid comprising at least a portion of the removed contaminant;and separating the mixture to produce a hydrocarbon effluent and a richhydrocarbon-immiscible lactamium ionic liquid effluent comprising therich hydrocarbon-immiscible lactamium ionic liquid. Thehydrocarbon-immiscible lactamium ionic liquid comprises at least one of:

a reaction product of a lactam compound having a general formula

wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms,an amine, an ether, or a silyl group, n is 1 to 8,

and a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, anda metal halide;

with the proviso that when n is 3, R is not hydrogen;

or

a reaction product of a lactam compound having a general formula

wherein the ring has at least one C—C double bond, R is hydrogen, analkyl group having from 1 to 12 carbon atoms, an amine, an ether, or asilyl group, n is 1 to 8,

and a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, anda metal halide;

or

a reaction product of a lactam compound having a general formula

wherein R is hydrogen or an alkyl group having from 1 to 12 carbonatoms, an amine, an ether, or a silyl group, n is 1 to 8, m is 1 to 8,and the rings can be saturated or unsaturated;

and a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, anda metal halide.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified flow scheme illustrating various embodiments ofthe invention.

FIGS. 2A and 2B are simplified flow schemes illustrating differentembodiments of an extraction zone of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In general, the invention may be used to remove contaminants from ahydrocarbon stream using a lactamium based ionic liquid.

The hydrocarbon stream typically has a boiling point in the range ofabout 30° C. to about 525° C. Examples of hydrocarbon streams include,but are not limited to, at least one of vacuum gas oil streams, lightcycle oil streams, naphtha streams, coker gas oil streams, kerosenestreams, streams made from biorenewable sources, fracking condensatestreams, streams from hydrocracking zones, streams from hydrotreatingzones, and streams from fluid catalytic cracking zones.

The term “contaminant” means one or more species found in thehydrocarbon material that is detrimental to further processing.Contaminants include, but are not limited to, nitrogen, sulfur, metals(e.g., nickel, iron, and vanadium) and Conradson carbon residue orcarbon residue. The metals content of such components, for example, maybe in the range of 100 ppm to 2,000 ppm by weight or more, the totalsulfur content may range from 0.1 to 7 wt %, the nitrogen content may befrom about 40 ppm to 30,000 ppm, and the API gravity may range fromabout −5° to about 35°. The Conradson carbon residue of such componentsis generally less than 30 wt %.

The ionic liquid can remove one or more of the contaminants in thehydrocarbon feed. The hydrocarbon feed will usually comprise a pluralityof nitrogen compounds of different types in various amounts. Thus, atleast a portion of at least one type of nitrogen compound may be removedfrom the hydrocarbon feed. The same or different amounts of each type ofnitrogen compound can be removed, and some types of nitrogen compoundsmay not be removed. In an embodiment, the nitrogen content of thehydrocarbon feed is reduced by at least about 3 wt %, at least about 5wt %, or at least about 10 wt %, or at least about 15 wt %, at leastabout 20 wt %, or at least about 30 wt %, or at least about 40 wt %.

The hydrocarbon feed will typically also comprise a plurality of sulfurcompounds of different types in various amounts. Thus, at least aportion of at least one type of sulfur compound may be removed from thehydrocarbon feed. The same or different amounts of each type of sulfurcompound may be removed, and some types of sulfur compounds may not beremoved. When the ionic liquid is made with a Brønsted acid only, thereis little sulfur removal. More sulfur removal occurs when the ionicliquid anion contains a halometallate. In an embodiment, the sulfurcontent of the hydrocarbon feed is reduced by at least about 1 wt %, orat least about 2 wt %, or at least 3 wt %, or at least 5 wt %, or atleast 10 wt %, or at least 20 wt %, or at least 30 wt %, or at least 35wt %, or at least 40 wt %.

The hydrocarbon feed will usually contain various metals, including, butnot limited to, nickel, iron, and vanadium. In an embodiment, the metalcontent of the hydrocarbon feed can be reduced by at least about 10% onan elemental basis, or at least about 20 wt %, or at least about 25 wt%, or at least about 30 wt %, or at least about 40 wt %, or at leastabout 50%. The metal removed may be part of a hydrocarbon molecule orcomplexed with a hydrocarbon molecule.

The nitrogen content may be determined using ASTM method D4629-02, TraceNitrogen in Liquid Petroleum Hydrocarbons by Syringe/Inlet OxidativeCombustion and Chemiluminescence Detection. The sulfur content may bedetermined using ASTM method D5453-00, Ultraviolet Fluorescence. Themetals content may be determined by UOP389-09, Trace Metals in Oils byWet Ashing and ICP-OES. The Conradson carbon residue may be determinedby ASTM D4530. Unless otherwise noted, the analytical methods usedherein such as ASTM D5453-00 and UOP389-09 are available from ASTMInternational, 100 Barr Harbor Drive, West Conshohocken, Pa., USA.

Processes according to the invention remove contaminants fromhydrocarbon streams. That is, the process removes at least onecontaminant. It is understood that the hydrocarbon will usually comprisea plurality of contaminants of different types in various amounts. Thus,the process removes at least a portion of at least one type ofcontaminant. The process may remove the same or different amounts ofeach type of contaminant, and some types of contaminants may not beremoved.

Lactamium base ionic liquids are used to extract one or morecontaminants from the hydrocarbon stream. Lactamium based ionic liquidssuitable for use in the instant invention are immiscible in thehydrocarbon stream being treated. As used herein the term “immiscibleionic liquid” means the formation of two phases that can be separated.

Lactam compounds can be converted to ionic liquids through reactionswith strong acids followed by a second reaction with a metal halide ifneeded, as described in U.S. application Ser. No. ______, entitledSynthesis of Lactam Based Ionic Liquids, filed on even date herewith(Attorney Docket No. H0042599), and U.S. application Ser. No. ______,entitled Synthesis of N-Alkyl Lactam Based Ionic Liquids, filed on evendate herewith (Attorney Docket No. H0042600), each of which isincorporated herein by reference.

The ionic liquids have a lactam cation. One type of lactamium basedionic liquid catalyst has the general formula:

wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms,an amine, an ether, or a silyl group, n is 1 to 8, and X⁻ is an aniongroup of a Brønsted acid HX or a halometallate; with the proviso thatwhen n is 3, R is not hydrogen.

In one embodiment, when n is 3, X⁻ is p-toluenesulfonate, and R is analkyl group, the alkyl group has from 1 to 5 carbon atoms.

In one embodiment, when n is 3, X⁻ is not a zinc halometallate.

Another way to represent this compound is:

wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms,an amine, an ether, or a silyl group, n is 1 to 8, and X⁻ is an aniongroup of a Brønsted acid HX or a halometallate.

Formula (I) is intended to cover both representations.

Another type of lactamium based ionic liquid has the general formula:

wherein the ring has at least one C—C double bond, R is hydrogen, analkyl group having from 1 to 12 carbon atoms, an amine, an ether, or asilyl group, n is 1 to 8, and X⁻ is an anion group of a Brønsted acid HXor a halometallate.

The ring has at least one double bond. Larger rings may have more thanone double bond. The double bond can be between any two adjacent carbonscapable of forming a double bond.

Another way to represent this compound is

wherein the ring has at least one C—C double bond, R is hydrogen, analkyl group having from 1 to 12 carbon atoms, an amine, an ether, or asilyl group, n is 1 to 8, and X⁻ is an anion group of a Brønsted acid HXor a halometallate.

Formula (II) is intended to cover both representations.

Examples of Formula (II) ionic liquids include, but are not limited to,1,5-dihydro-pyrrol-2-one ionic liquids,1,5-dihydro-1-methyl-2H-pyrrol-2-one based ionic liquids,1,3-dihydro-2H-pyrrol-one ionic liquids, and1,3-dihydro-1-methyl-2H-pyrrol-2-one based ionic liquids.

Another type of lactamium based ionic liquid has the general formula:

wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms,an amine, an ether, or a silyl group, n is 1 to 8, m is 1 to 8, X⁻ is ananion group of a Brønsted acid HX or a halometallate, and the rings canbe saturated or unsaturated.

The heterocyclic ring (ring with n) can be saturated or unsaturated. Thehydrocarbon ring (ring with m) can be saturated, unsaturated, oraromatic. If the ring is unsaturated, the C—C double bond can be betweenany two adjacent carbons capable of forming a double bond. There can beone or more C—C double bonds in either ring or in both rings.

Another way to represent this compound is

wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms,an amine, an ether, or a silyl group, n is 1 to 8, m is 1 to 8, X⁻ is ananion group of a Brønsted acid HX or a halometallate, and the rings canbe saturated or unsaturated.

Formula (III) is intended to cover both representations.

Examples of Formula (III) ionic liquids include, but are not limited to,octahydro-2H-indol-2-one ionic liquids,octahydro-1-methyl-2H-indol-2-one based ionic liquids, and 2-oxindoleionic liquids, and 1,3-dihydro-1-methyl-2H-indol-2-one based ionicliquids.

Suitable X⁻ groups include, but are not limited to, carboxylates,nitrates, phosphates, phosphinates, phosphonates, imides, cyanates,borates, sulfates (including bisulfates), sulfonates (includingfluoroalkanesulfonates), acetates, halides, halometallates, andcombinations thereof. Examples include, but are not limited to,following tetrafluoroborate, triflate, trifluoroacetate, chloroacetate,nitrate, hydrogen sulfate, hydrogen phosphate, dicyanoimide,methylsulfonate, and combinations thereof. Suitable halides include, butare not limited to, bromide, chloride, and iodide. Halometallates aremixtures of halides, such as bromide, chloride, and iodide, and metals.Suitable metals include, but are not limited to, Sn, Al Zn, Mn, Fe, Ga,Cu, Ni, and Co. In some embodiments, the metal is aluminum, with themole fraction of aluminum ranging from 0<Al<0.25 in the anion. Suitableanions include, but are not limited to, AlCl₄ ⁻, Al₂Cl₇ ⁻, Al₃Cl₁₀ ⁻,AlCl₃Br⁻, Al₂Cl₆Br⁻, Al₃Cl₉Br⁻, AlBr₄ ⁻, Al₂Br₇ ⁻, Al₃Br₁₀ ⁻, GaCl₄ ⁻,Ga₂Cl₇ ⁻, Ga₃Cl₁₀ ⁻, GaCl₃Br⁻, Ga₂Cl₆Br⁻, Ga₃Cl₉Br⁻, CuCl₂ ⁻, Cu₂Cl₃ ⁻,Cu₃Cl₄ ⁻, ZnCl³⁻, FeCl₃ ⁻ FeCl₄ ⁻, Fe₃Cl₇ ⁻, PF₆ ⁻, and BF₄ ⁻ .

In some embodiments when making a halometallate, the lactamium compoundis reacted with a Brønsted acid HX, such as HCl, where X is a halide toform a lactam halide. The lactam halide is then reacted with a metalhalide to form the lactam halometallate.

As is understood by those of skill in the art, the particular Brønstedacid used will depend on the anion desired. Suitable Brønsted acidsinclude for example, sulfuric acid, p-toluenesulfonic acid, hydrochloricacid, hydrobromic acid, nitric acid, phosphoric acid, tetrafluoroboricacid, triflic acid, trifluoroacetic acid, chloroacetic acid, andmethanesulfonic acid.

The lactamium ionic liquid comprises at least one of:

a reaction product of a lactam compound having a general formula

wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms,an amine, an ether, or a silyl group, n is 1 to 8;

and a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, anda metal halide;

with the proviso that when n is 3, R is not hydrogen;

or

a reaction product of a lactam compound having a general formula

wherein the ring has at least one C—C double bond, R is hydrogen, analkyl group having from 1 to 12 carbon atoms, an amine, an ether, or asilyl group, n is 1 to 8,

and a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, anda metal halide;

or

a reaction product of a lactam compound having a general formula

wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms,an amine, an ether, or a silyl group, n is 1 to 8, m is 1 to 8, and therings can be saturated or unsaturated;

and a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, anda metal halide.

A lactamium based ionic liquid can be made by reacting a lactam compoundhaving a general formula

wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms,an amine, an ether, or a silyl group, and n is 1 to 8;

with a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, anda metal halide.

Another lactamium based ionic liquid can be made by reacting a lactamcompound having a general formula

wherein the ring has at least one C—C double bond, R is hydrogen, analkyl group having from 1 to 12 carbon atoms, an amine, an ether, or asilyl group, and n is 1 to 8,

with a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, anda metal halide.

Another lactamium based ionic liquid can be made by reacting a lactamcompound having a general formula

wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms,an amine, an ether, or a silyl group, n is 1 to 8, m is 1 to 8, and therings can be saturated or unsaturated;

with a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, anda metal halide.

The heterocyclic ring (ring with n) can be saturated or unsaturated. Thehydrocarbon ring (ring with in) can be saturated, unsaturated, oraromatic. If the ring is unsaturated, the C—C double bond can be betweenany two adjacent carbons capable of forming a double bond. There can beone or more C—C double bonds in either ring or in both rings.

The reaction can take place at temperatures in the range of about −36°C. to the decomposition temperature of the ionic liquid, or about −20°C. to less than the decomposition temperature of the ionic liquid, orabout 0° C. to about 200° C., or about 0° C. to about 150° C., or about0° C. to about 120° C., or about 20° C. to about 80° C.

The reaction typically takes place at atmospheric pressure, althoughhigher or lower pressures could be used if desired.

When making halometallate compounds, the reaction should take place inan inert atmosphere.

The reaction typically takes about 1 min to multiple days, depending onthe ionic liquid. Those made with the Brønsted acid typically takeminutes to hours, while the halometallates typically take minutes to oneor more days.

The reaction may be practiced in laboratory scale experiments throughfull scale commercial operations. The process may be operated in batch,continuous, or semi-continuous mode.

In some embodiments, the reaction can take place in the absence of asolvent. In other embodiments, it can take place in the presence of asolvent. The contacting can take place in the presence of one or moresolvents. Suitable solvents for non-halometallate ionic liquids include,but are not limited to water, toluene, dichloromethane, liquidcarboxylic acids such as acetic acid or propanoic acid, alcohols, suchas methanol and ethanol, and combinations thereof. When water is used asthe solvent, an additional product may form. The products can beseparated using known separation techniques Non-protic solvents, such asdichloromethane, are suitable for use with halometallates.

The ratio of the Brønsted acid to the lactam compound is about 1:1 toabout 3:1. In some embodiments, when making a halometallate using aBrønsted acid followed by the addition of a metal halide, the ratio ofBrønsted acid to the lactam compound is about 1:1. In general,increasing the lactam:acid ratio increased the contaminant removal.

Consistent with common terms of art, the ionic liquid introduced to thecontaminant removal step may be referred to as a “lean lactamium ionicliquid” generally meaning a hydrocarbon-immiscible lactamium ionicliquid that is not saturated with one or more extracted contaminants.Lean lactamium ionic liquid may include one or both of fresh andregenerated lactamium ionic liquid and is suitable for accepting orextracting contaminants from the hydrocarbon feed. Likewise, thelactamium ionic liquid effluent may be referred to as “rich lactamiumionic liquid”, which generally means a hydrocarbon-immiscible lactamiumionic liquid effluent produced by a contaminant removal step or processor otherwise including a greater amount of extracted contaminants thanthe amount of extracted contaminants included in the lean lactamiumionic liquid. A rich lactamium ionic liquid may require regeneration ordilution, e.g. with fresh lactamium ionic liquid, before recycling therich lactamium ionic liquid to the same or another contaminant removalstep of the process.

In an embodiment, the invention is a process for removing contaminantsfrom a hydrocarbon feed stream comprising a contacting step and aseparating step. In the contacting step, a hydrocarbon feed streamcomprising a contaminant and a hydrocarbon-immiscible lactamium ionicliquid are contacted or mixed. The contacting may facilitate transfer orextraction of the one or more contaminants from the hydrocarbon feedstream to the lactamium ionic liquid. Although a lactamium ionic liquidthat is partially soluble in the hydrocarbon may facilitate transfer ofthe contaminant from the hydrocarbon to the ionic liquid, partialsolubility is not required. Insoluble hydrocarbon/lactamium ionic liquidmixtures may have sufficient interfacial surface area between thehydrocarbon and lactamium ionic liquid to be useful. In the separationstep, the mixture of hydrocarbon and lactamium ionic liquid settles orforms two phases, a hydrocarbon phase and a lactamium ionic liquidphase, which are separated to produce a hydrocarbon-immiscible lactamiumionic liquid effluent and a hydrocarbon effluent.

The process may be conducted in various equipment which is well known inthe art and is suitable for batch or continuous operation. For example,in a small scale form of the invention, hydrocarbon and ahydrocarbon-immiscible lactamium ionic liquid may be mixed in a beaker,flask, or other vessel, e.g., by stirring, shaking, use of a mixer, or amagnetic stirrer. The mixing or agitation is stopped and the mixtureforms a hydrocarbon phase and a lactamium ionic liquid phase which canbe separated, for example, by decanting, centrifugation, or use of apipette to produce a hydrocarbon effluent having a lower contaminantcontent relative to the incoming hydrocarbon. The process also producesa hydrocarbon-immiscible lactamium ionic liquid effluent comprising theone or more contaminants.

The contacting and separating steps may be repeated, for example, whenthe contaminant content of the hydrocarbon effluent is to be reducedfurther to obtain a desired contaminant level in the ultimatehydrocarbon product stream from the process. Each set, group, or pair ofcontacting and separating steps may be referred to as a contaminantremoval step. Thus, the invention encompasses single and multiplecontaminant removal steps. A contaminant removal zone may be used toperform a contaminant removal step. As used herein, the term “zone” canrefer to one or more equipment items and/or one or more sub-zones.Equipment items may include, for example, one or more vessels, heaters,separators, exchangers, conduits, pumps, compressors, and controllers.Additionally, an equipment item can further include one or more zones orsub-zones. The contaminant removal process or step may be conducted in asimilar manner and with similar equipment as is used to conduct otherliquid-liquid wash and extraction operations. Suitable equipmentincludes, for example, columns with: trays, packing, rotating discs orplates, and static mixers. Pulse columns and mixing/settling tanks mayalso be used.

FIG. 1 is a flow scheme illustrating various embodiments of theinvention and some of the optional and/or alternate steps and apparatusencompassed by the invention. Hydrocarbon stream 2 andhydrocarbon-immiscible lactamium ionic liquid stream 4 are introduced toand contacted and separated in contaminant removal zone 100 to producehydrocarbon-immiscible lactamium ionic liquid effluent stream 8 andhydrocarbon effluent stream 6 as described above. The lactamium ionicliquid stream 4 may be comprised of fresh lactamium ionic liquid stream3 and/or one or more lactamium ionic liquid streams which are recycledin the process as described below. In an embodiment, a portion or all ofhydrocarbon effluent stream 6 is passed via conduit 10 to a hydrocarbonconversion zone 800. Hydrocarbon conversion zone 800 may, for example,comprise at least one of a fluid catalytic cracking and a hydrocrackingprocess, which are well known in the art.

The contact step can take place at a temperature in the range of about20° C. to the decomposition temperature of the lactamium based ionicliquid, or about 20° C. to about 120° C., or about 20° C. to about 80°C.

The contacting time is sufficient to obtain good contact between thelactamium based ionic liquid and the hydrocarbon feed. The contactingtime is typically in the range of about 1 min to about 1 hr, or about 5min to about 30 min.

An optional hydrocarbon washing step may be used, for example, torecover lactamium ionic liquid that is entrained or otherwise remains inthe hydrocarbon effluent stream by using water to wash or extract theionic liquid from the hydrocarbon effluent. In this embodiment, aportion or all of hydrocarbon effluent stream 6 (as feed) and a waterstream 12 (as solvent) are introduced to hydrocarbon washing zone 400.The hydrocarbon effluent and water streams introduced to hydrocarbonwashing zone 400 are mixed and separated to produce a washed hydrocarbonstream 14 and a spent water stream 16, which comprises the lactamiumionic liquid. The hydrocarbon washing step may be conducted in a similarmanner and with similar equipment as used to conduct other liquid-liquidwash and extraction operations as discussed above. Various hydrocarbonwashing step equipment and conditions such as temperature, pressure,times, and solvent to feed ratio may be the same as or different fromthe contaminant removal zone equipment and conditions. In general, thehydrocarbon washing step conditions will fall within the same ranges asgiven below for the contaminant removal step conditions. A portion orall of the washed hydrocarbon stream 14 may be passed to hydrocarbonconversion zone 800.

An optional lactamium ionic liquid regeneration step may be used, forexample, to regenerate the ionic liquid by removing the contaminant fromthe ionic liquid, i.e. reducing the contaminant content of the richlactamium ionic liquid. In an embodiment, a portion or all ofhydrocarbon-immiscible lactamium ionic liquid effluent stream 8 (asfeed) comprising the contaminant and a regeneration solvent stream 18are introduced to ionic liquid regeneration zone 500. Thehydrocarbon-immiscible lactamium ionic liquid effluent stream 8 andregeneration solvent stream 18 are mixed and separated to produce anextract stream 20 comprising the contaminant, and a regeneratedlactamium ionic liquid stream 22. The lactamium ionic liquidregeneration step may be conducted in a similar manner and with similarequipment as used to conduct other liquid-liquid wash and extractionoperations as discussed below. Various lactamium ionic liquidregeneration step conditions such as temperature, pressure, times, andsolvent to feed may be the same as or different from the contaminantremoval conditions. In general, the ionic liquid regeneration stepconditions will fall within the same ranges as given below for thecontaminant removal step conditions.

In an embodiment, the regeneration solvent stream 18 comprises ahydrocarbon fraction lighter than the hydrocarbon and which isimmiscible with the lactamium ionic liquid. The lighter hydrocarbonfraction may consist of a single hydrocarbon compound or may comprise amixture of hydrocarbons. In an embodiment, the lighter hydrocarbonfraction comprises at least one of a naphtha, gasoline, diesel, lightcycle oil (LCO), and light coker gas oil (LCGO) hydrocarbon fraction.The lighter hydrocarbon fraction may comprise straight run fractionsand/or products from conversion processes such as hydrocracking,hydrotreating, fluid catalytic cracking (FCC), reforming, coking, andvisbreaking. In this embodiment, extract stream 20 comprises the lighterhydrocarbon regeneration solvent and the contaminant. In anotherembodiment, the regeneration solvent stream 18 comprises water, and theionic liquid regeneration step produces extract stream 20 comprising thecontaminant and regenerated hydrocarbon-immiscible lactamium ionicliquid 22 comprising water and the lactamium ionic liquid. In anembodiment wherein regeneration solvent stream 18 comprises water, aportion or all of spent water stream 16 may provide a portion or all ofregeneration solvent stream 18. Regardless of whether regenerationsolvent stream 18 comprises a lighter hydrocarbon fraction or water, aportion or all of regenerated hydrocarbon-immiscible lactamium ionicliquid stream 22 may be recycled to the contaminant removal step via aconduit not shown consistent with other operating conditions of theprocess. For example, a constraint on the water content of thehydrocarbon-immiscible lactamium ionic liquid stream 4 or the lactamiumionic liquid/hydrocarbon mixture in contaminant removal zone 100 may bemet by controlling the proportion and water content of fresh andrecycled ionic liquid streams

Optional ionic liquid drying step is illustrated by drying zone 600. Theionic liquid drying step may be employed to reduce the water content ofone or more of the streams comprising ionic liquid to control the watercontent of the contaminant removal step as described above. In theembodiment of FIG. 1, a portion or all of regeneratedhydrocarbon-immiscible lactamium ionic liquid stream 22 is introduced todrying zone 600. Although not shown, other streams comprising ionicliquid such as the fresh lactamium ionic liquid stream 3,hydrocarbon-immiscible lactamium ionic liquid effluent stream 8, andspent water stream 16, may also be dried in any combination in dryingzone 600. To dry the lactamium ionic liquid stream or streams, water maybe removed by one or more various well known methods includingdistillation, flash distillation, and using a dry inert gas to stripwater. Generally, the drying temperature may range from about 100° C. toless than the decomposition temperature of the ionic liquid, usuallyless than about 300° C. The pressure may range from about 35 kPa(g) toabout 250 kPa(g). The drying step produces a driedhydrocarbon-immiscible lactamium ionic liquid stream 24 and a dryingzone water effluent stream 26. Although not illustrated, a portion orall of dried hydrocarbon-immiscible lactamium ionic liquid stream 24 maybe recycled or passed to provide all or a portion of thehydrocarbon-immiscible lactamium ionic liquid introduced to contaminantremoval zone 100. A portion or all of drying zone water effluent stream26 may be recycled or passed to provide all or a portion of the waterintroduced into hydrocarbon washing zone 400 and/or ionic liquidregeneration zone 500.

FIG. 2A illustrates an embodiment of the invention which may bepracticed in contaminant removal or extraction zone 100 that comprises amulti-stage, counter-current extraction column 105 wherein hydrocarbonand hydrocarbon-immiscible lactamium ionic liquid are contacted andseparated. The hydrocarbon feed stream 2 enters extraction column 105through feed inlet 102 and lean lactamium ionic liquid stream 4 entersextraction column 105 through ionic liquid inlet 104. In the FIGURES,reference numerals of the streams and the lines or conduits in whichthey flow are the same. Hydrocarbon feed inlet 102 is located belowionic liquid inlet 104. The hydrocarbon effluent passes throughhydrocarbon effluent outlet 112 in an upper portion of extraction column105 to hydrocarbon effluent conduit 6. The hydrocarbon-immisciblelactamium ionic liquid effluent including the contaminants removed fromthe hydrocarbon feed passes through lactamium ionic liquid effluentoutlet 114 in a lower portion of extraction column 105 to lactamiumionic liquid effluent conduit 8.

FIG. 2B illustrates another embodiment of contaminant removal washingzone 100 that comprises a contacting zone 200 and a separation zone 300.In this embodiment, lean lactamium ionic liquid stream 4 and hydrocarbonfeed stream 2 are introduced into the contacting zone 200 and mixed byintroducing hydrocarbon feed stream 2 into the flowing lean lactamiumionic liquid stream 4 and passing the combined streams through staticin-line mixer 155. Static in-line mixers are well known in the art andmay include a conduit with fixed internals such as baffles, fins, andchannels that mix the fluid as it flows through the conduit. In otherembodiments, not illustrated, lean lactamium ionic liquid stream 4 maybe introduced into hydrocarbon feed stream 2, or the lean lactamiumionic liquid stream 4 and hydrocarbon feed stream may be combined suchas through a “y” conduit. In another embodiment, lean lactamium ionicliquid stream 4 and hydrocarbon feed stream 2 are separately introducedinto the static in-line mixer 155. In other embodiments, the streams maybe mixed by any method well known in the art, including stirred tank andblending operations. The mixture comprising hydrocarbon and lactamiumionic liquid is transferred to separation zone 300 via transfer conduit7. Separation zone 300 comprises separation vessel 165 wherein the twophases are allowed to separate into a rich lactamium ionic liquid phasewhich is withdrawn from a lower portion of separation vessel 165 vialactamium ionic liquid effluent conduit 8 and a hydrocarbon phase whichis withdrawn from an upper portion of separation vessel 165 viahydrocarbon effluent conduit 6. Separation vessel 165 may comprise aboot, not illustrated, from which rich lactamium ionic liquid iswithdrawn via conduit 8.

Separation vessel 165 may contain a solid media 175 and/or othercoalescing devices which facilitate the phase separation. In otherembodiments, the separation zone 300 may comprise multiple vessels whichmay be arranged in series, parallel, or a combination thereof. Theseparation vessels may be of any shape and configuration to facilitatethe separation, collection, and removal of the two phases. In a furtherembodiment, contaminant removal zone 100 may include a single vesselwherein lean lactamium ionic liquid stream 4 and hydrocarbon feed stream2 are mixed, then remain in the vessel to settle into the hydrocarboneffluent and rich lactamium ionic liquid phases.

In an embodiment, the process comprises at least two contaminant removalsteps. For example, the hydrocarbon effluent from one contaminantremoval step may be passed directly as the hydrocarbon feed to a secondcontaminant removal step. In another embodiment, the hydrocarboneffluent from one contaminant removal step may be treated or processedbefore being introduced as the hydrocarbon feed to the secondcontaminant removal step. There is no requirement that each contaminantremoval zone comprises the same type of equipment. Different equipmentand conditions may be used in different contaminant removal zones.

The contaminant removal step may be conducted under contaminant removalconditions including temperatures and pressures sufficient to keep thehydrocarbon-immiscible lactamium ionic liquid and hydrocarbon feeds andeffluents as liquids. For example, the contaminant removal steptemperature may range between about 10° C. and less than thedecomposition temperature of the lactamium ionic liquid, and thepressure may range between about atmospheric pressure and about 700kPa(g). When the hydrocarbon-immiscible ionic liquid comprises more thanone lactamium ionic liquid component, the decomposition temperature ofthe lactamium ionic liquid is the lowest temperature at which any of thelactamium ionic liquid components decompose. The contaminant removalstep may be conducted at a uniform temperature and pressure or thecontacting and separating steps of the contaminant removal step may beoperated at different temperatures and/or pressures. In an embodiment,the contacting step is conducted at a first temperature, and theseparating step is conducted at a temperature at least 5° C. lower thanthe first temperature. In a non-limiting example, the first temperatureis about 80° C. Such temperature differences may facilitate separationof the hydrocarbon and lactamium ionic liquid phases.

The above and other contaminant removal step conditions such as thecontacting or mixing time, the separation or settling time, and theratio of hydrocarbon feed to hydrocarbon-immiscible lactamium ionicliquid (lean lactamium ionic liquid) may vary greatly based, forexample, on the specific lactamium ionic liquid or liquids employed, thenature of the hydrocarbon feed (straight run or previously processed),the contaminant content of the hydrocarbon feed, the degree ofcontaminant removal required, the number of contaminant removal stepsemployed, and the specific equipment used. In general, it is expectedthat contacting time may range from less than one minute to about twohours; settling time may range from about one minute to about eighthours. The weight ratio of hydrocarbon feed to lean lactamium ionicliquid introduced to the contaminant removal step may range from about1:10,000 to about 10,000:1, or about 1:1,000 to about 1,000:1, or about1:100 to about 100:1, or about 1:20 to about 20:1, or about 1:10 toabout 10:1. In an embodiment, the weight of hydrocarbon feed is greaterthan the weight of lactamium ionic liquid introduced to the contaminantremoval step.

In an embodiment, a single contaminant removal step reduces thecontaminant content of the hydrocarbon by more than about 10 wt %, ormore than about 20 wt %, or more than about 30 wt %, or more than about40 wt %, or more than about 50 wt %, or more than about 60 wt %, or morethan about 70 wt %, or more than about 75 wt %, or more than about 80 wt%, or more than about 85 wt %, or more than about 90 wt %. As discussedherein, the invention encompasses multiple contaminant removal steps toprovide the desired amount of contaminant removal.

The degree of phase separation between the hydrocarbon and lactamiumionic liquid phases is another factor to consider as it affects recoveryof the lactamium ionic liquid and hydrocarbon. The degree of contaminantremoved and the recovery of the hydrocarbon and lactamium ionic liquidmay be affected differently by the nature of the hydrocarbon feed, thevariations in the specific lactamium ionic liquid or liquids, theequipment, and the contaminant removal conditions such as thosediscussed above.

The amount of water present in the hydrocarbon/hydrocarbon-immisciblelactamium ionic liquid mixture during the contaminant removal step mayalso affect the amount of contaminant removed and/or the degree of phaseseparation, i.e., recovery of the hydrocarbon and lactamium ionicliquid. In an embodiment, the hydrocarbon/hydrocarbon-immisciblelactamium ionic liquid mixture has a water content of less than about10% relative to the weight of the lactamium ionic liquid, or less thanabout 5% relative to the weight of the lactamium ionic liquid, or lessthan about 2% relative to the weight of the ionic liquid. In a furtherembodiment, the hydrocarbon/hydrocarbon-immiscible lactamium ionicliquid mixture is water free, i.e., the mixture does not contain water.

Unless otherwise stated, the exact connection point of various inlet andeffluent streams within the zones is not essential to the invention. Forexample, it is well known in the art that a stream to a distillationzone may be sent directly to the column, or the stream may first be sentto other equipment within the zone such as heat exchangers, to adjusttemperature, and/or pumps to adjust the pressure. Likewise, streamsentering and leaving contaminant removal, washing, and regenerationzones may pass through ancillary equipment such as heat exchanges withinthe zones. Streams, including recycle streams, introduced to washing orextraction zones may be introduced individually or combined prior to orwithin such zones.

The invention encompasses a variety of flow scheme embodiments includingoptional destinations of streams, splitting streams to send the samecomposition, i.e. aliquot portions, to more than one destination, andrecycling various streams within the process. Examples include: variousstreams comprising ionic liquid and water may be dried and/or passed toother zones to provide all or a portion of the water and/or ionic liquidrequired by the destination zone. The various process steps may beoperated continuously and/or intermittently as needed for a givenembodiment e.g. based on the quantities and properties of the streams tobe processed in such steps. As discussed above the invention encompassesmultiple contaminant removal steps, which may be performed in parallel,sequentially, or a combination thereof. Multiple contaminant removalsteps may be performed within the same contaminant removal zone and/ormultiple contaminant removal zones may be employed with or withoutintervening washing, regeneration and/or drying zones.

By the term “about,” we mean within 10% of the value, or within 5%, orwithin 1%.

Example

The example is presented to further illustrate some aspects and benefitsof the invention and is not to be considered as limiting the scope ofthe invention.

A LCO feed containing 597 ppm nitrogen was added to caprolactamiumhydrogen sulfate ionic liquid in a 10:1 ratio of LCO feed:ionic liquid.The mixture was stirred at room temperature. After 1 hr, the stirringwas stopped, and the LCO feed and the ionic liquid were allowed toseparate. The LCO feed was decanted away from the ionic liquid layer.The experiment was repeated at different molar ratios ofcaprolactam:acid.

The experiments were repeated using a naphtha feed containing 49 ppmnitrogen.

The results are shown in Table 1.

TABLE 1 Nitrogen Removal Molar Ratio LCO Feed Naphtha Feed 1:1 36 wt %78 wt % 1:7 61 wt % 94 wt % 1:3 75 wt % 83 wt %

While at least one exemplary embodiment has been presented in theforegoing detailed description of the invention, it should beappreciated that a vast number of variations exist. It should also beappreciated that the exemplary embodiment or exemplary embodiments areonly examples, and are not intended to limit the scope, applicability,or configuration of the invention in any way. Rather, the foregoingdetailed description will provide those skilled in the art with aconvenient road map for implementing an exemplary embodiment of theinvention. It being understood that various changes may be made in thefunction and arrangement of elements described in an exemplaryembodiment without departing from the scope of the invention as setforth in the appended claims.

What is claimed is:
 1. A process for removing a contaminant from a hydrocarbon stream comprising: contacting the hydrocarbon stream comprising the contaminant with a lean hydrocarbon-immiscible lactamium ionic liquid to produce a mixture comprising the hydrocarbon and a rich hydrocarbon-immiscible lactamium ionic liquid comprising at least a portion of the removed contaminant; and separating the mixture to produce a hydrocarbon effluent and a rich hydrocarbon-immiscible lactamium ionic liquid effluent comprising the rich hydrocarbon-immiscible lactamium ionic liquid; wherein the hydrocarbon-immiscible lactamium ionic liquid comprises at least one of: a reaction product of a lactam compound having a general formula

wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8; and a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, and a metal halide; with the proviso that when n is 3, R is not hydrogen; or a reaction product of a lactam compound having a general formula

wherein the ring has at least one C—C double bond, R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8, and a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, and a metal halide; or a reaction product of a lactam compound having a general formula

wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8, in is 1 to 8, and the rings can be saturated or unsaturated; and at least one of a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, and a metal halide.
 2. The process of claim 1 wherein the lactam reaction product is at least one of carboxylates, nitrates, phosphates, phosphinates, phosphonates, imides, cyanates, borates, sulfates, sulfonates, acetates, and halides.
 3. The process of claim 1 wherein the lactam reaction product is the halometallate and wherein a metal in the halometallate is at least one of Sn, Al, Zn, Mn, Fe, Ga, Cu, Ni, and Co.
 4. The process of claim 1 wherein a ratio of the Brønsted acid HX to the lactam compound is about 1:1 to about 3:1.
 5. The process of claim 1 wherein the hydrocarbon stream has a boiling point in a range of about 30° C. to about 525° C.
 6. The process of claim 1 wherein the contacting step is conducted at a temperature in a range of about 20° C. to about 80° C.
 7. The process of claim 1 further comprising passing at least a portion of the hydrocarbon effluent to a hydrocarbon conversion process.
 8. The process of claim 1 further comprising: regenerating the rich hydrocarbon-immiscible lactamium ionic liquid effluent; and recycling the regenerated hydrocarbon-immiscible lactamium based ionic liquid to the contacting step.
 9. The process of claim 1 wherein a ratio of the hydrocarbon to the hydrocarbon-immiscible lactamium ionic liquid is in a range of about 1:1,000 to about 1,000:1.
 10. The process of claim 1 further comprising contacting the rich hydrocarbon-immiscible lactamium ionic liquid effluent with a regeneration solvent to form an extract stream comprising the contaminant and a stream of lean hydrocarbon-immiscible lactamium ionic liquid.
 11. The process of claim 10 wherein the regeneration solvent comprises water, naphtha, gasoline, diesel, light cycle oil, and light coker gas oil.
 12. The process of claim 10 further comprising separating the stream of lean hydrocarbon-immiscible lactamium ionic liquid from the regeneration solvent.
 13. The process of claim 12 further comprising recycling the stream of lean hydrocarbon-immiscible lactamium ionic liquid to the contacting step.
 14. The process of claim 13 reactivating the stream of lean hydrocarbon-immiscible lactamium ionic liquid with an acid before recycling the stream of lean hydrocarbon-immiscible lactamium ionic liquid to the contacting step.
 15. The process of claim 1 wherein the ionic liquid has the general formula (III) and wherein at least one ring has at least one C—C double bond.
 16. A process for removing a contaminant from a hydrocarbon stream comprising: contacting the hydrocarbon stream comprising the contaminant with a lean hydrocarbon-immiscible lactamium ionic liquid to produce a mixture comprising the hydrocarbon and a rich hydrocarbon-immiscible lactamium ionic liquid comprising at least a portion of the removed contaminant; and separating the mixture to produce a hydrocarbon effluent and a rich hydrocarbon-immiscible lactamium ionic liquid effluent comprising the rich hydrocarbon-immiscible lactamium ionic liquid; regenerating the rich hydrocarbon-immiscible lactamium ionic liquid effluent to form a stream of lean hydrocarbon-immiscible lactamium ionic liquid; recycling the stream of lean hydrocarbon-immiscible lactamium ionic liquid to the contacting step; and passing at least a portion of the hydrocarbon effluent to a hydrocarbon conversion process; wherein the hydrocarbon-immiscible lactamium ionic liquid comprises at least one of: a reaction product of a lactam compound having a general formula

wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8; and a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, and a metal halide; with the proviso that when n is 3, R is not hydrogen; or a reaction product of a lactam compound having a general formula

wherein the ring has at least one C—C double bond, R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8, and a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, and a metal halide; or a reaction product of a lactam compound having a general formula

wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8, in is 1 to 8, and the rings can be saturated or unsaturated; and a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, and a metal halide.
 17. The process of claim 16 wherein regenerating the rich hydrocarbon-immiscible lactamium ionic liquid effluent comprises contacting the rich hydrocarbon-immiscible lactamium ionic liquid effluent with a regeneration solvent to form an extract stream comprising the contaminant and the stream of lean hydrocarbon-immiscible lactamium ionic liquid.
 18. The process of claim 16 reactivating the stream of lean hydrocarbon-immiscible lactamium ionic liquid with an acid before recycling the stream of lean hydrocarbon-immiscible lactamium ionic liquid to the contacting step.
 19. The process of claim 17 wherein the lactam reaction product is at least one of carboxylates, nitrates, phosphates, phosphinates, phosphonates, imides, cyanates, borates, sulfates, sulfonates, acetates, and halides.
 20. The process of claim 17 wherein a ratio of the Brønsted acid HX to the lactam compound is about 1:1 to about 3:1. 